Desperate for acceptance, Zoidberg lives with a continuing delusion that he is well regarded by the rest of the Planet Express crew. He does appear to be rather intelligent, but he is an inept medical practitioner. Most of his co-workers look down on him, especially Hermes, who likes to make his life even more miserable. Dr. Zoidberg is Professor Farnsworth's oldest friend, which suggests that Zoidberg is much older than he appears. A citizen of Earth, he loves his chosen home planet for the personal freedom it provides.[4ACV05] He is also apparently the only intelligent organism on Earth deemed nice by the Robot Santa Claus.[2ACV04] It is unknown why, but it may be because of a glitch in Santa or because of Zoidberg's kind and innocent personality. Other than the professor, the only people known to identify him as a friend are the members of the First Planet Express crew, Fry (sometimes), Mom and his girlfriend.

Dr. Zoidberg was born on Decapod 10 and attended high school there, where he had a crush on classmate Edna.[2ACV05] During that time, his face was covered in barnacles, for which he was laughed at.

As a youngster, Zoidberg wanted to become a comedian, following the footsteps of his uncle Harold Zoid, but he was discouraged by his guardian,[1] whereupon he developed an interest in medical science.[3ACV08] Though he formulated a new plan to impress his family by becoming a doctor, he was again scolded for giving up his dream of being a comedian. Eventually, he went to medical school and left his home planet to seek his fortune on Earth, although it is not known whether he studied on Decapod 10 or on Earth. He never received a doctorate in medicine for humans, but rather, in art history.[6ACV05] Though fully incompetent with humans, he treats them anyway, both at Planet Express and, apparently, outside the company (one such patient being the Australian man) . He is however, an expert on aliens, as stated by Professor Farnsworth.[6ACV18]

In 2927, Zoidberg met Professor Hubert J. Farnsworth while on a mission to capture a Tritonian yeti for Mom. During the mission, the Professor was infected with hypermalaria, which at the time, was thought to be impossible to cure. The Professor saved Zoidberg's life by killing the yeti. In exchange, Farnsworth pleaded that Zoidberg kill him as soon as the symptoms of hypermalaria started, so he wouldn't have to experience the horrible suffering.[6ACV18] Zoidberg agreed, leading to his employment at Planet Express in 2961, when it was founded.[6ACV15]

During Xmas of 3000, Zoidberg was the only person on Earth deemed "nice" by Robot Santa and was given a pogo stick as his present.[2ACV04] In 3001, Zoidberg saved Fry's life by transplanting his head onto Amy's shoulder when his body was severely damaged in a car crash on Jupiter's moon Europa.[2ACV07]

In 3001, Zoidberg was filling with male jelly and becoming violent due to the approaching mating season for his species. He went to his home planet to find a mate, and soon became intent on sharing the ritual with his old classmate Edna. Edna was disinterested and more attracted to Fry so Zoidberg challenged Fry to the Decapodian tradition of Claw-Plach. He intended to kill Fry until he noticed the mating ritual had begun without him, so he and Fry returned to Earth as friends again.[2ACV05]

Later that year, when he was trapped at the bottom of the ocean with the rest of the Planet Express crew, he found a shell to live in and planned to reside there permanently, until it somehow burned down after Bender left his cigar next to it.[2ACV12]

Although his medical career meant giving up his dream of becoming a comedian, Zoidberg has since tried on occasion to be a freelance comedian of some sort, but lack the necessary talent and sense of humour. In his biggest try, he even had a minor part in his uncle's film The Magnificent Three in 3002.[3ACV08]

When the crew had to explore Fry's body in 3002, Zoidberg made himself useful by using his limited knowledge of human anatomy to lead them through a capillary.[3ACV02] Also that year he began coughing up pearls which were sold as necklaces while the crew were following Bender on tour.[3ACV13]

After a supernova he was accidentally sent back in time to 1947 Roswell where he was captured by the US Army. He met President Harry Truman (it is unclear which of them was more baffled by the other) and was partially vivisected. He was rescued by Fry and returned to the future where he put his organs back in (except a non-vital one) and fixed himself with duct tape.[3ACV19]

In 3003 on Freedom Day, he ate an Earthican flag and was chased by an angry mob sent by President Nixon. He took refuge in his planet's embassy and was sentenced to death for his crime while in hiding. In response, the Decapodians invaded and conquered Earth, enslaving all its citizens. Eventually, Zoidberg disagreed with the takeover and helped defeat the invaders with a burning flag.[4ACV05]

In 3004, after an accident in a health spa, he reverted back to all his childhood stages until he returned to his current age in the Fountain of Aging.[4ACV09]

When Professor Farnsworth created a box containing a parallel universe, Zoidberg quickly befriended his parallel counterpart. The two Zoidbergs, fed up with how the crew treats them, stole the box containing our universe and tried to escape into other universes until they were caught by Farnsworth.[4ACV15]

When everyone on Earth was given a 300 dollar government refund, Zoidberg was inspired to live like a rich person, until he was mocked by Mom for thinking the money had a lot of worth. He eventually spent his money on food for a group of homeless people.[4ACV16]

In 3011, the rest of the crew became fed up with Dr. Zoidberg's incompetence as a doctor, and demanded that the Professor fire him.[6ACV18] However, the symptoms of hypermalaria had after several decades, finally began to infect him. Farnsworth approached Zoidberg and informed him that it was time to perform the mercy killing, only it needed to be by surprise. But before Zoidberg could carry out the act, the rest of the crew caught Zoidberg trying to kill the Professor and imprisoned him in his office, restraining him with the Professor's lab coat. On the coat, Zoidberg discovers a thin, white, yeti hair, and realizes that the Professor never had hypermalaria, but yetiism, a dangerous disease with identical symptoms to hypermalaria, that turns the victim into a yeti. Shocked by this revelation, Zoidberg escapes and goes to the headquarters of Mom, where he exchanges a coupon for a free tanning session for the disembodied head of a yeti. Zoidberg returns to the Planet Express headquarters just moments before the rest of the crew kill the Professor themselves, (after he revealed the truth to them) Zoidberg reveals to them that the Professor has yetiism, not hypermalaria. Using the pineal gland from the yeti's head, he creates an antidote and forces him to swallow it; just as the yeti transformation begins. The cure was successful, and the rest of the crew apologize to Zoidberg for treating him so poorly.

Norm, Sam and Sadie, parents,[3ACV08] presumably one is the woman who raised him,[4ACV05] the other two are deceased biological parents. It is also possible that Decapodians have three biological parents. He referred to one of them (his mother) as a saint, which was most likely just an expression. Non-canonically, his parents' original intentions were for him to become a Lawyer.[US#048]

His brother Norman and up to nine other siblings that budded from Zoidberg during the coral stage of his larval stadium. A duplicate Norman dies when he is sucked into the Fountain of Aging, but all other siblings are never mentioned again.[4ACV09]

The original inspiration and the basic traits and characteristics were developed by David X. Cohen,[3] while the cartoon design was created by Matt Groening. The later refinement and addition of various traits came from the various writers.[4]

Cohen's name for Dr. Zoidberg came from a video game he had developed during the 1980s, called "Zoid",[3] which was largely inspired by the popular arcade game Qix.[5] Cohen tried to get the then famous publisher Brøderbund to publish the game.[5] Unfortunately, Brøderbund refused to publish Cohen's assembly-written game, and he shelved it.[5] Dr. Zoidberg was thus named to honour those wasted years in college.[3]

Cohen's inspiration came from Bones McCoy from Star Trek, the doctor on the U.S.S. Enterprise. Bones was often faced with treating aliens and other non-humans, including Spock.[3] Cohen's idea for Zoidberg was the exact opposite, where an alien would perform on humans.[3] Zoidberg's trait of being a bad doctor was then established.[4]

As the show progresses, Zoidberg's apparent utility becomes less obvious, and the Planet Express staff shun his presence from one instance to another.

It has been mentioned several times that the Planet Express crew openly abuses him. In Bender's Big Score, he yelled that Fry was the only crew member who had never struck him. Also, several times he has done something wrong and exclaimed "Don't hit me!"

As with all Decapodians, Zoidberg's mannerisms, speech, and personality are representative of dry East Coast humor readily seen in Jewish communities.

He claims to have lost his medical degree in a volcano. This, however, was an excuse for not having one to give to Cubert.

In earlier episodes he is animated with teeth, but in later episodes he is drawn without. His mouth frills are prehensile and can move independently, although most of the time they remain loose.

Is apparently his own medical corporation, as described on the door to his office.

Zoidberg has a top fin or crest on his head that appears at times of emotional duress, such as "Why Must I Be a Crustacean in Love?" and Bender's Big Score. It seems to be linked to his species' equivalent to testosterone, as it appears to be linked to both aggression and arousal, as shown in Bender's Game and "Attack of the Killer App". Also, the fin appears when he remembers a forgotten event. The crest, referred to by Amy as "cockateiling", has been shown on one occasion to occur just before a traumatic event, allowing Zoidberg to predict danger, but not with enough notice to do anything about it.

His greatest fantasy is to be a grandmother ("Subjugated yet honored!").

Hermes from the earliest episodes seems to harbor a bitter hatred toward Zoidberg, never explained or given a rationale. This starts in "Hell Is Other Robots", when Hermes states someone (in fact Bender was addicted to it) has been using a lot of electricity, then blames Zoidberg who exclaims "MEEE?" Hermes later removes the office's salt-water cooler to save money, prompting Zoidberg to blurt out, "This is a witch-hunt!"

He is noted by Farnsworth to be a "doctor for aliens", often gives mistaken diagnoses on Fry and Bender that may apply to other species, and has demonstrated knowledge of alien physiology (as shown in "The Tip of the Zoidberg"). This may suggest he qualified as a doctor on Decapod 10. He was also described as a "medical doctor" by the Contrabulous Choosematron, implying he may be qualified in some form as a doctor.

Interesting, the only thing about being a doctor Zoidberg seems to know about is reattaching limbs, as he does this several times.[2ACV05][2ACV07][BBS]

He has shown infrequent romantic interest in human men, thought this probably means nothing as he is repeatedly unable to differentiate between human genders.

In Bender's Big Score he was crowned Prince of Bageria by the Scammers. Although it's obivously a scam, Zoidberg still fell for it.

Zoidberg appears to think humans have multiple mouths, dorsal fins. He also can't tell humans apart from robots and males from females. He also thinks that food is digested in the heart.

Several of Zoidberg's internal organs are either redundant or vestigial. In "Roswell that Ends Well", he is vivisected by scientists who know nothing of his physiology and leaves one of his hearts behind.

He may be a fan of Scooby-Doo, as he said "Well gang, it looks like we have another mystery on our hands.", a catchphrase of Fred.[3ACV06]

According to the Contrabulous Choosematron, Zoidberg is "delicious with butter and lemon",[7ACV02] though this could be a gag since those two do work well with lobster.

He can harmonize with himself, possibly with two sets of vocal cords.

He is one of three current crew members of Planet Express that have worked for Mom in some capacity, the other two being Farnsworth and Hermes.

He is unable to swim very well, and does a "doggie paddle" instead of a proper stroke.

Zoidberg: Look, coupons! I can get two oil changes for the price of one. Now, if I could only afford the one... and the car. Ah, the years! So many memories, so many strange fluids gushing out of patients' bodies.

Bender: I'll just do the cutting.Zoidberg: You do and I'll [bleep] []i] [Ng gut you like a fish!.]

Professor Farnsworth: No. I'm afraid the Smellescope isn't powerful enough. Bender's odour is so mild it's being overpowered by local sources.[He, Fry and Leela glare at Zoidberg who jumps up and claps with delight.]Zoidberg: Hooray! People are paying attention to me!

Zoidberg: Only $14.99 for a two-record set. Two records! Oh, Zoidberg, at last you're becoming a crafty consumer!Man: [on phone] Hello?Zoidberg: Hello? I'll take eight![Time lapse.]Tinny Tim: [shouting] Extra! Extra! Greatest opera of all time sucks.Zoidberg: I'll take eight!

Hermes: Strange. Usually you don't know anything about human anatomy.Zoidberg: I learned it from a decongestant commercial. [echoing] "Soothing action, action, action, action..."

Professor Farnsworth: So many loves half-loved. So many inventions half-invented. That damn time machine alone set me back fifteen years.Zoidberg: If only it'd worked, you could go back and not waste your time on it.

Also, he is usually shown to be highly unintelligent when it comes to being a doctor, such as thinking that Amy is the father of Leela's poppler, that humans have multiple mouths, that Fry is a robot, and that humans digest food in their hearts. More so, he often mistakes the human penis for other objects, especially that of Hermes. The closest he has ever been to showing competence in the field of human medical science was in "Parasites Lost", but only because he saw it in a commercial.